P-2 Cell Biology and Biotechnology — Science STD 10 — Question

When the branches of a plant growing in the field are pulled towards the ground and a part of them is covered with moist soil (leaving the tips of the branches exposed above the ground), then after some time new roots develop from the parts of branches buried in the soil. On cutting these branches from the parent plant, new plants are produced from the cut parts of branches which had developed roots.

1. What is this method of propagation of plants known as?
2. What type of branches should a plant have to be able to be propagated by this method?
3. Name any two plants which are grown for their flowers and propagated by this method.
4. Name any two plants which are grown for their fruits and propagated by this method.
5. Name one plant which gets propagated by this method naturally by forming runners (soft horizontal stems running above the ground).

In case of sexual reproduction, newborn shows similarities about characters. Explain this statement with suitable example.

Which are the effects of dry famine?

In a Std. X class, out of 40 students, 10 students use spectacles, 2 students have ( positive power and 8 students have negative power of lenses in their spectacles.
Answer the following questions:
(1) What does the negative power indicate?
(2) What does the positive power indicate?
(3) Generally which type of spectacles do most of the students use?
(4) What defect of eyesight do most of the students suffer from?
(5) Give two possible reasons for the above defect.

A filamentous alga X is found in ponds, lakes and slow-moving streams. The filament of this alga simply breaks into two (or more) pieces on maturing and each piece then grows to become a complete new alga.

1. Name an alga which X is likely to be.
2. What is the colour of X?
3. What is the method of forming new algae by the breaking of parent alga known as?
4. An Amoeba also breaks up to form two daughter Amoebae. What is the difference in the splitting of Amoeba and splitting of this alga as a method of reproduction?
5. Name one marine animal which reproduces in the same way as alga X.

Explain the application of heating effect of electric current in an electric iron.

Water and dissolved minerals get into the root hair of a plant by a process called A and enter the conducting tissue B. The process C helps the water and dissolved minerals to move up through the tissue B in roots and stem, and reach the leaves of a plant. In the leaves food is made by a process D. This food is then transported to all the parts of a plant through tissue E. The process of distributing food made in the leaves to all the parts of the plants is called F.

1. What are (i) A, (ii) B, (iii) C, (iv) D, (v) E, and (vi) F?
2. Which tissue is made up of living cells: B or E?
3. Which tissue, B or E, contains sieve tubes?
4. Which tissue, B or E, contains tracheids?

State and explain the various methods for preventing or retarding rancidity of food.